Improved centrifuge tube



March 1963 K. GAUSLAA 3,081,029

IMPROVED CENTRIFUGE TUBE Filed June 19, 1959 INVENTOR. KJETIL GAUSLAA A TTORNE YS United States Patent 3,03LOZ9 Patented Mar. 12, 1963 ice 3,081,029 p w IMPROVED CENTREFUGE' TUBE Kjetil' Gausl'aa, Baton Rouge, 1a., assignor to Copolymcr Rubber & Chemical Corporation, a corporation of Louisiana 7 Filed June 19, 1959, Ser. No. 821,579 1 Claims. (Cl. 233-26) This invention relates. to centrifuge tubesand, in one of its more specific aspects, to an improved centrifuge tube which is especially useful in obtaining samples for use in analytical work;

Centrifuge tubes of the type most commonly 'used at the present time are constructed of glassor plastic. Such tubes are unsatisfactory foruse in'high'speed centrifuges due'tofg lass breakage or flow of plastic at the extremely "high' centrifugal forces-encountered. In addition, the prior a'rtcentrifuge tubes have been constructed so" as to be completely closed off at the-lower end. This co struction made 'it. impossible to withdraw a component directly from 'any'porti'on'of the "tube otherthan the top and" required that an instrument be inserted through the component in the upper portion of the tube in instances where it wasdesired toobtain a sample of a heavy component' from the bottom of the tube.

The foregoing has resulted "in inherent disadvantages in certain fields such as in he analysis of serum in latex. For example, the serum of latex is heavier than the remainingcomponent and it hasbeen impossiblehereto- "fore to obtain a centrifuged sample of serum without contaminating it withlighter components and thereby "rendering the subsequent analysis inaccurate. The art 'has long sought a satisfactory centrifuge tube overcoming the above-mentioned disadvantages and yet which 'is sulficiently strong to withstand the extremely high centrifugal forces encountered when used in an ultra high speed centrifuge. However, prior to the, present invention such a centrifuge tube has not been available in spite of the great need.

It is' an object of the present invention to provide an improved centrifuge tube.

,Itis afurther objectof'the present invention to provide unimproved centrifuge tube, whereby a desired component of a liquid mixture separable into its componentsby centrifuging may be obtained substantially free of a remaining component or components.

It is still a further object of the present invention to provide a metallic centrifuge tube having the above mentioned desirablefeatures and which also overcomes the disadvantages of the prior artglass and plastic centrifuge' tubes.

.It is still a further object of the present invention .to provide an improved centrifuge tube capable of withstanding high centrifugal forces, the tube having a closed lower end provided with an axially aligned opening which is scaled by means of a readily penetrable gasket whcre- =by asharp instrument such as a hypodermic needle may be inssrtedtherethrough for the purpose of withdrawing :asamplefrom the lower portion of the tube without danget of contamination with a lighter component in the upper portion of the tube.

Still other .objects of thepresent invention and the attendant advantages will be apparent to those skilled in the art uponreference to the following detailed description and the drawing, wherein:

FlGURE/l is-a side view in elevationof a centrifuge tubeconstructed in accordance withone presently preferred embodiment ofthe present invention;

FIGURE 2 'is a cross-sectional view of the centrifuge tube of FIGURE 1 taken along the line Z -Z;

2 FIGURES is an exploded view of the centrifuge tube of FIGURE 1 showing the componentparts thereof;

FIGURE 4 illustrates the'centrifuge'tube of the present invention in place in the'tube'holde'rs therefor of a prior art centrifuge with the centrifuge being at res-t;

FIGURES illustrates the centrifuge ofFIGURE 4, with the centrifuge tube of the present invention in place inthe tube holders,'when operating athigh speedduring the centrifuging operation; and

FIGURE 6 illustrates the manner in which the heavier component in the lower portion of the centrifuge tube may be withdrawn after the centrifuge operation 'by means of a hypodermic syringe. Y

Referring now to FIGURES 1; 2 and 3, the centrifuge tube generally designated as lll com'pri'se's an elongated tubularmember 11 which may be open at its upper end 12 and closed at its lower or-bottom end portion 14. A neck portion 16 of reduced crosssection extends downward from the bottom, wall 15 of centrifuge tube 16 forming an annular shoulder-17'thereon'. The neck portion as is provided with threads 18'anda circularrecess 19 is forrnrdin its outer end, the recess being of reduced cross section and centrallyarranged thereby forming annular shoulder 22. In addition, a small axially aligned opening 2% extends through the bottom wall 15 and neck portion 16 with its interior terminus 23 opening into the tube interior 2i and its exterior terminus 24 opening into recess 19. The recess 1-9and shoulder 17 are provided with a sealing member or gasket-25 which is retained in position by means of cup-shaped nut member 26 provided with internal threads 27 for receiving the threads 18 on neck portion 16 in threaded engagement. The nut '26 is provided with a smalla'xially aligned opening 28 35which is, in ali nment with opening'20 and internal flat surface 29 engaging the lower surface of gasketZS. In addition, the nut member 26- may be provided with portion 39 for the purpose of allowing the nut 26 to be tightened easily and italsomay be of such a depth so as toprovide for a space at 3'1 and thus assure that adequate pressure is applied on gasket 25 when the nut is tightened.

The gasket 25 is preferably constructed of a soft resilicut sealing material which is readily penetrable by means of a hypodermic needle such as rubber, including natural and synthetic, and the like. Preferably, a solvent resistant, self-sealing type of rubber such as polychloroprene or butadiene-acryloritrile elastomers of the Buna' N type is preferred since the opening made upon insertion of the hypodermic needle will be rescaled after its withdrawal thereby allowing the gasket to be use! a number of times before leakage occurs. The use of self-sealing rubber will greatly prolong the life of a single gasket but, in instances Where this is not necessary or desirable, any suitable material readily penetrable by means of a hypodermicneedle may be used. When the gasket 25 is ready for replacement, the nut 26 is removed, the old gasket lifted out and then replaced with anew gasket. The ease of replacement andextremely low'co'st of the gasket is an especially desirable feature.

The gasket 25may be constructed in one piece and so as to provide a relativelythick circular portion 34 suring engagement'with shoulder '17 with th'eirelatively thick portion 34 being seated in recess 19. Thus, centrifugal forces are free to act only on the relatively thick portion 34 which is much stronger than the flange portion 35.

Referring now to FIGURE 4, centrifuge tube is so designed as to be inserted in tube holders 44) of centrifuge 41. The centrifuge machine 41 may be of any suitable prior art type with centrifuge tubes emobdying the principles of the ers 40. Either slow speed, medium speed, high speed or ultra high speed centrifuge machines may be used. The centrifuge 41 illustrated in the drawings is provided with motor 42 and centrifuge arms 43 terminating on their outer ends in tube holders 40. The tube holders 40 are pivoted on the outer ends of arms 43 by means of pins 44 and the centrifuge tubes 10 are inserted therein. The tubes 10 may be of a slightly longer length than tube holders 40, thereby providing an upper end 45 extending invention being designed to fit the tube holdthereabove for allowing easyremoval after the centrifuging operation.

Upon reference to FIGURE 5, it will be noted that the centrifuge machine 41 is in operation and the arms 43 are being rotated rapidly in the direction of the arrow with the tubes 10 being partially filled with a liquid such as latex or other emulsion to be separated into its components. The pivoted tube holders 40 are moved upward from the FIGURE 4 position by centrifugal force and into horizontal alignment with arms 43. Loss of liquid from tubes 10 does not occur due to centrifugal force.

. During the centrifuging operation, the heavier component of the material being centrifuged is forced toward the bottom of the centrifuge tubes, while the lighter component tends to rise toward the upper portion of the tubes.

Referring now to FIGURE 6, centrifuge tube 10, has been removed from tube holder 40 after the centrifuging operation and the desired heavy component contained in the lower portion thereof is in the process of being recovered by means of empty hypodermic syringe 46 provided with needle 47. The hypodermic needle 47 has been inserted through opening 28, gasket and opening 20 into lower portion 14 of interior 21. The hypodermic syringe 46 is now operated in the usual manner to fill it with liquid, i.e., by pulling out on plunger operator 48, to thereby obtain a sample of the desired heavy component for analysis or other use that is free of contamination with lighter component.

The size of the openings 20 and 28 may vary over wide limits. For example, the openings 20 and 28 should be sufficiently large to receive the hypodermic needle or other suitable equivalent instrument for penetrating the gasket 25 and withdrawing a sample from the lower portion of the centrifuge tube, but the openings should not be sufiiciently large so as to cause undue displacement or tearing of gasket 25 with accompanying leakage due to high centrifugal forces and lack of support for the gasket 25 in the area covered by the openings at the point of contact with the gasket. When using the usual hypodermic needles and syringes of commerce, openings of about 0.04-0.2 inch at the point of contact with the gasket 25 are generally very satisfactory.

The centrifuge tube 10 may be constructed of suitable materials other than metal such as plastics in instances where such materials are suitable, e.g., for low to medium speed centrifuging operations. However, for high speed or ultra high speed centrifuging operations it may be desirable to construct the tube of a metal suitable for withstanding the high forces involved. For example, stainless steel or other machinable ferrous metals, brass, aluminum or high strength aluminum alloys, and alloys or metals in general characterized by high strength may be used.

The centrifuge tube of the present invention is highly satisfactory for obtaining serum samples from latex which are free of contamination. For example, centrifuging latex at ultra high speeds results in a top layer which is composed of a heavy, creamy material and it is impossible to remove an uncontaminated sample of serum from the lower portion of the centrifuge tube by inserting an instrument through the upper layer. The present invention provides a centrifuge tube which allows a serum sample to be withdrawn from the lower portion of the tube without contamination with the heavy, creamy layer. Thus, a serum sample obtained in accordance with the present invention may be analyzed for soap by either conductometric titration or colorimetric titration methods well known in the art and the soap content determined with high accuracy.

The foregoing detailed description and the illustrative drawing are for purposes of illustration only and are not to be taken as limiting to the scope of the appended claims.

What is claimed is:

1. A centrifuge tube comprising a cylindrical tubular member, the tubular member being closed at one end to form the bottom of the centrifuge tube, the bottom of the centrifuge tube having a threaded neck portion extending outward therefrom, the outer end of the neck portion having a recess formed therein with the recess being surrounded by a shoulder, the bottom of the centrifuge tube including the neck portion having a small first opening extending therethrough, the opening being of a size such as to allow passage of a hypodermic needle therethrough and thereby provide access to the interior of the tube, the exterior terminus of the first opening being located in the recess formed in the neck portion, a sealing member formed of a resilient sealing material readily penetrable by means of a hypodermic needle, the sealing member including a relatively thick portion and a flange portion of reduced thickness, the relatively thick portion of the sealing member being seated in the recess formed in the neck portion with the flange portion of reduced thickness being in contact with the shoulder surrounding the recess, the flange portion of the sealing member being in effective sealing relationship with the shoulder surrounding the recess, and inter nally threaded cup-shaped nut means in threaded engagement with the neck portion, the cup-shaped nut means having an internal surface engaging the sealing member for supporting the relatively thick portion of the sealing member and retaining the flange portion of the sealing member in effective sealing relationship with the shoulder, the cup-shaped nut means having a small opening formed therethrough in axial alignment with the first opening for receiving a hypodermic needle and together with the first opening providing access to the interior of the tube, the internal surface of the cup-shaped nut means being in contact with the sealing member and supporting against outward displacement substantially the entire surface area of the flange portion and relatively thick portion with the exception of the area of the opening in the cup-shaped nut means, and the sealing member being of unitary construction whereby access to the interior of the tube through the first opening and the opening formed in the nut means is attainable only by first penetrating through the sealing material.

2. A centrifuge tube comprising a metallic tubular member, the cylindrical tubular member being closed at one end to form the bottom of the centrifuge tube, the bottom of the centrifuge tube having a threaded metallic neck portion extending outward therefrom, the outer end of the neck portion having a recess formed therein with the recess being surrounded by a shoulder, the bottom of the centrifuge tube including the neck portion having a small first opening extending therethrough, the opening being of a size such as to allow passage of a hypodermic needle therethrough and thereby provide access to the interior of the tube, the exterior terminus of the first opening being located in the recess formed in the neck portion, a self-sealing member formed of a resilient rubbery polymer, the self-sealing member including a relatively thick portion and a flange portion of reduced thickness, the relatively thick portion of the self-sealing member being seated in the recess formed in the neck portion with the flange portion of reduced thickness being in contact with the shoulder surrounding the recess, the flange portion of the self-sealing member being in effective sealing relationship with the shoulder surrounding the recess, and internally threaded metallic cup-shaped nut means in threaded engagement with the neck portion, the cup-shaped nut means having an internal surface engaging the self-sealing member for supporting the relatively thick portion of the self-sealing member and retaining the flange portion of the sealing member in effective sealing relationship with the shoulder, the cup-shaped nut means having a small opening formed therethrough in axial alignment with the first opening for receiving a hypodermic needle and together with the first opening providing access to the interior of the tube, the internal surface of the cup-shaped nut means being in contact with the sealing member and supporting against outward displacement substantially the entire surface area of the flange portion and relatively thick portion with the exception of the area of the opening in the cup-shaped nut means, and the sealing member being of unitary construc tion whereby access to the interior of the tube through the first opening and the opening formed in the nut means is attainable only by first penetrating through the sealing material.

3. A centrifuge tube comprising a cylindrical tubular member, the tubular member being closed at one end to form the bottom of the centrifuge tube, the bottom of the centrifuge tube having a threaded neck portion extending outward therefrom, the outer end of the neck portion having a recess of reduced cross section formed therein with the recess being surrounded by a shoulder, the bottom of the centrifuge tube including the neck portion having a small first opening extending therethrough, the opening being of a size such as to allow passage of a hypodermic needle therethrough and thereby provide access to the interior of the tube, the exterior terminus of the first opening being located in the recess formed in the neck portion, a sealing member formed of a resilient sealing material readily penetrable by means of a hypodermic needle, the sealing member including a relatively thick portion and a flange portion of reduced thickness, the relatively thick portion of the sealing member being seated in the recess formed in the neck portion with the flange portion of reduced thickness being in contact with the shoulder surrounding the recess, the flange portion of the sealing member being in effective sealing relationship with the shoulder surrounding the recess, and internally threaded cup-shaped nut means in threaded engagement with the neck portion, the cupshaped nut means having a flat internal surface engaging the sealing member under pressure for supporting the relatively thick portion of the sealing member and retaining the flange portion of the sealing member in effective sealing relationship with the shoulder, the cup-shaped nut means having a small opening formed therethrough in axial alignment with the first opening for receiving a hypodermic needle and together with the first opening providing access to the interior of the tube, the fiat internal surface of the cup-shaped nut means applying pressure to the sealing member and supporting against outward displacement substantially the entire surface area of the flange portion and relatively thick portion with the exception of the area of the opening in the cup-shaped nut means, the relatively thick portion of the sealing member filling substantially the entire recess and having a thickness greater than the depth of the recess whereby pressure is applied thereto by the flat internal surface of the cup-shaped nut means, and the sealing member being of unitary construction whereby access to the interior of the tube through the first opening and the opening formed in the nut means is attainable only by first penetrating through the sealing material. I

4. A centrifuge tube comprising a metallic cylindrical tubular member, the tubular member being closed at one end to form the bottom wall of the centrifuge tube, the bottom wall of the centrifuge tube having a threaded metallic neck portion extending outward therefrom, the outer end of the neck portion having a recess of reduced cross section formed therein with the recess being surrounded by a shoulder, the bottom wall of the centrifuge tube including the neck portion having a small first opening extending therethrough, the opening being of a size such as to allow passage of a hypodermic needle therethrough and thereby provide access to the interior of the tube, the exterior terminus of the first opening being located in the recess formed in the neck portion, a sealing member formed of a resilient rubbery polymer, the sealing member including a relatively thick portion and a flange portion of reduced thickness, the relatively thick portion of the sealing member being seated in the recess formed in the neck portion with the flange portion of reduced thickness being in contact with the shoulder surrounding the recess, the flange portion of the sealing member being in effective sealing relationship with the shoulder surrounding the recess, and internally threaded metallic cup-shaped nut means in threaded engagement with the neck portion, the cup-shaped nut means having a flat internal surface engaging the sealing member under pressure for supporting the relatively thick portion of the sealing member and retaining the flange portion in effective sealing relationship with the shoulder, the cupshaped nut means having a small opening formed there'- through in axial alignment with the first opening for receiving a hypodermic needle and together with the first opening providing access to the interior of the tube, the flat internal surface of the cup-shaped nut means applying pressure to the sealing member and supporting against outward displacement substantially the entire surface area of the flange portion and relatively thick portion with the exception of the area of the opening in the cup-shaped nut means, the relatively thick portion of the sealing member filling substantially the entire recess and having a thickness greater than the depth of the recess whereby pressure is applied thereto by the flat internal surface of the cup-shaped nut means, and the sealing member being of unitary construction whereby access to the interior of the tube through the first opening and the opening formed in the nut means is attainable only by first penetrating through the sealing material.

References Cited in the file of this patent UNITED STATES PATENTS 302,565 Hoyt July 29, 1884 1,424,187 Seelman Aug. 1, 1922 2,820,590 Walker Jan. 21, 1958 2,861,570 Beecher Nov. 25, 1958 2,876,775 Barr et a1. Mar. 10, 1959 FOREIGN PATENTS 565,193 Germany Nov. 29, 1932 903,384 Germany Feb. 4, 1954 1,074,398 France Mar. 31, 1954 

1. A CENTRIFUGE TUBE COMPRISING A CYLINDRICAL TUBULAR MEMBER, THE TUBULAR MEMBER BEING CLOSED AT ONE END TO FORM THE BOTTOM OF THE CENTRIFUGE TUBE, THE BOTTOM OF THE CENTRIFUGE TUBE HAVING A THREADED NECK PORTION EXTENDING OUTWARD THEREFROM, THE OUTER END OF THE NECK PORTION HAVING A RECESS FORMED THEREIN WITH THE RECESS BEING SURROUNDED BY A SHOULDER, THE BOTTOM OF THE CENTRIFUGE TUBE INCLUDING THE NECK PORTION HAVING A SMALL FIRST OPENING EXTENDING THERETHROUGH, THE OPENING BEING OF A SIZE SUCH AS TO ALLOW PASSAGE OF A HYPODERMIC NEEDLE THERETHROUGH AND THEREBY PROVIDE ACCESS TO THE INTERIOR OF THE TUBE, THE EXTERIOR TERMINUS OF THE FIRST OPENING BEING LOCATED IN THE RECESS FORMED IN THE NECK PORTION, A SEALING MEMBER FORMED OF A RESILIENT SEALING MATERIAL READILY PENETRABLE BY MEANS OF A HYPODERMIC NEEDLE, THE SEALING MEMBER INCLUDING A RELATIVELY THICK PORTION AND A FLANGE PORTION OF REDUCED THICKNESS, THE RELATIVELY THICK PORTION OF THE SEALING MEMBER BEING SEATED IN THE RECESS FORMED IN THE NECK PORTION WITH THE FLANGE PORTION OF REDUCED THICKNESS BEING IN CONTACT WITH THE SHOULDER SURROUNDING THE RECESS, THE FLANGE PORTION OF THE SEALING MEMBER BEINS IN EFFECTIVE SEALING RELATIONSHIP WITH THE SHOULDER SURROUNDING THE RECESS, AND INTERNALLY THREADED CUP-SHAPED NUT MEANS IN THREADED ENGAGEMENT WITH THE NECK PORTION, THE CUP-SHAPED NUT MEANS HAVING AN INTERNAL SURFACE ENGAGING THE SEALING MEMBER FOR SUPPORTING THE RELATIVELY THICK PORTION OF THE SEALING MEMBER AND RETAINING THE FLANGE PORTION OF THE SEALING MEMBER IN EFFECTIVE SEALING RELATIONSHIP WITH THE SHOULDER, THE CUP-SHAPED NUT MEANS HAVING A SMALL OPENING FORMED THERETHROUGH IN AXIAL ALIGNMENT WITH THE FIRST OPENING FOR RECEIVING A HYPODERMIC NEEDLE AND TOGETHER WITH THE FIRST OPENING PROVIDING ACCESS TO THE INTERIOR OF THE TUBE, THE INTERNAL SURFACE OF THE CUP-SHAPED NUT MEANS BEING IN CONTACT WITH THE SEALING MEMBER AND SUPPORTING AGAINST OUTWARD DISPLACEMENT SUBSTANTIALLY THE ENTIRE SURFACE AREA OF THE FLANGE PORTION AND RELATIVELY THICK PORTION WITH THE EXCEPTION OF THE AREA OF THE OPENING IN THE CUP-SHAPED NUT MEANS, AND THE SEALING MEMBER BEING OF UNITARY CONSTRUCTION WHEREBY ACCESS TO THE INTERIOR OF THE TUBE THROUGH THE FIRST OPENING AND THE OPENING FORMED IN THE NUT MEANS IS ATTAINABLE ONLY BY FIRST PENETRATING THROUGH THE SEALING MATERIAL. 